Production of lubricating oils

ABSTRACT

LUBRICATING OIL AND GASOLINE ARE PRODUCED BY HYDROCRACKING A PETROLEUM FEEDSTOCK BOILING ABOVE 350*C. USING A CATALYST OF A HYDROGENATING METAL AND AN ALKALI METAL DEFICIENT FAUJASITE AT 350-450*C. AND 70-265 BARS GAUGE IN THE PRESENCE OF NH3 AND H2S WHICH ARE PREFERABLY PRODUCED BY USING A N&amp;S CONTAINING FEEDSTOCK. THE PREFERRED FAUJASITE CONTAINS AN AKALINE EARTH METAL, PARTICULARLY MAGNESIUM AND THE PREFERRED HYDROGENATING METAL IS 0.01-5% WT OF PT GROUP METAL. THE CONVERSION MAY BE FROM 40-95% WT., PARTICULARLY 60-95% WT. THE NH3 AND H2S MAY BE PRODUCED FROM THE FEEDSTOCK IN SITU OR PREFERABLY BY A PERLIMINARY DENITROGENATION AND DESULPHURIZATION WITH THE TOTAL EFFLUENT PASSING TO THE HYDROCRACKING ZONE.

United States Patent 3,804,742 PRODUCTION OF LUBRICATKNG OILS Robert Neil Bennett, Englefield Green, and David Richards, Sunbury-on-Thames, England, assignors to 'llhel British Petroleum Company Limited, London, Engan No Drawing. Filed April 2, 1973, Ser. No. 346,855 Claims priority, application Great Britain, April 17, 1972, 17,565/72 Int. Cl. C01b 33/28; C10g 13/02, 37/10 US. Cl. 208-111 9 C ABSTRACT OF THE DISCLOSURE Lubricating oil and gasoline are produced by hydrocracking a petroleum feedstock boiling above 350 C. using a catalyst of a hydrogenating metal and an alkali metal deficient faujasite at 350-450 C. and 70-265 bars gauge in the presence of NI-I and H 8 which are preferably produced by using a N&S containing feedstock.

The preferred faujasite contains an alkaline earth metal, particularly magnesium and the preferred hydrogenating metal is 0.01-% wt. of Pt group metal. The conversion may be from 40*95% wt., particularly 60-95% wt.

The NH and H S may be produced from the feedstock in situ or preferably by a preliminary denitrogenation and desulphurization with the total effluent passing to the hydrocracking zone.

This invention relates to the production of lubricating oils by hydrocatalytic treatment.

As conventionally practiced the production of lubricating oils requires the steps of solvent extraction to remove aromatics and improve viscosity index, solvent dewaxing to remove n-paraffins and improve pour point and a finishing treatment to improve color and color stability. It is known that the solvent extraction step can be replaced by a. hydrocatalytic treatment step using a catalyst of one or more hydrogenating metals on a refractory oxide support. Some breakdown of the feedstock is unavoidable in this hydrocatalytic treatment and gasoline, kerosine and gas oils are also recovered. These lower boiling products contain appreciable amounts of middle distillates as well as gasoline, which is of low octane number, and this type of by-product pattern is not always desirable.

The hydrocracking of petroleum fractions, including those boiling in the lubricating oil boiling range, over catalysts of a hydrogenating metal on a zeolite support is also known. The main product is gasoline of reasonable quality with less middle distillate. With this product pattern, the main emphasis has been on maximum conversion to gasoline.

There have been proposals, in U.S. Pat. No. 3,654,130 and French Pat. No. 2,077,334 (equivalent to German Often. 2,105,832), for using zeolite hydrocracking catalysts for the hydrocatalytic production of lubricating oils but the emphasis has been on limiting the extent of conversion to maximize the yield of lubricating oil and minimize the production of gasoline. US. Pat. No. 3,654,130, for example not only limits the conversion to less than 15% of product boiling below 650 F. (343 C.) to maximize yield, but states that limitation of the conversion is necessary because the viscosity index of the lubricating oil product decreases with increasing conversion.

The complete specification of U.K. application No. 26,307/70 (now US. Pat. 3,732,156) describes, however, a process for the production of both lubricating oil and gasoline by hydrocatalytic treatment of a petroleum feedice stock boiling above 350 C..over a zeolite catalyst. The zeolite specified is a decationized zeolite of the faujasite type preferably decationized to an extent of at least 50%, more particularly at least and the process preferably operates in the absence of NH and H 8.

It has now been found that the production of lubricating oil and gasoline by hydrocracking can be satisfactorily operated in the presence of NH and H 8 and that such operation is particularly desirable when using a fanjasite catalyst containing a significant amount of an alkaline earth metal.

According to the present invention therefore a process for the production of lubricating oil and gasoline by hydrocracking comprises contacting a petroleum feedstock containing a major proportion of material boiling above 350 C. at a temperature of 350 to 450 C., a pressure of 70 to 265 bars gauge, in the presence of hydrogen, and in the presence of ammonia and hydrogen sulphide, with a catalyst comprising a hydrogenating metal and an alkali metal deficient zeolite of the faujasite type and recovering a product boiling above 350 C. having an improved viscosity index and also a gasoline product boiling below 204 C.

The feedstock to the process is preferably a vacuum distillate boiling within the range 350-600 C. It may contain a minor proportion, preferably 5 to 30% wt., of catalytic cracker cycle oil. Since lubricating oils are marketed in several grades with relatively narrow boiling ranges, distillation to give relatively narrow boiling range cuts is required at some stage. In the present invention, a wide boiling range cut may be used as feedstock and distillation into narrower cuts given after hydrocatalytic treatment or distillation may take place before the hydrocatalytic treatment and individual cuts may be hydro treated. The former route has the advantage of avoiding blocked operation but the latter route has the advantage that optimum hydrotreating conditions may be chosen for each cut. If a vacuum residue fraction is used it should be deasphalted in the normal way.

The preferred temperature is 380 to 420 C. and the preferred pressure to 138 bars gauge. Other process conditions for the hydrocatalytic treatment over the zeolite catalyst may be chosen from the following ranges:

Space velocity, v./v./h.: 0.5 to 5.0, preferably 0.5 to 2.0 Hydrogen gas rate, m. /m. 450 to 3360, preferably 560 Clearly the conversion should be less than 100% wt. conversion to lower boiling products to give as one product a lubricating oil fraction boiling above 350 C. The extent of conversion will depend on the relative amounts of gasoline and lubricating oil required and the desired viscosity index of the lubricating oil. Increased conversion increases the viscosity index of the lubricating oil but reduces its yield. The conversion is preferably in the range 40-90% wt. conversion to products boiling below 350 C., more particularly 60-90% wt. conversion.

For the purposes of the present invention the conversion to products boiling below 350 C. is defined as:

100% wt. product boiling above 350 C. based on the weight of feedstock.

As indicated above, the presence of ammonia and hydrogen sulphide is a necessary feature of the process. In practice most petroleum feedstocks boiling above 350 C. contain combined nitrogen and sulphur which is converted to NH, and H 8 by hydrocatalytic treatment. Thus, while the NH and H 5 required can be added from external sources, in the preferred and normal course of events they are produced byemploying a nitrogen and sulphur containing feedstock, which is, preferably, treated in a preliminary catalytic denitrogenation and desulphurization step. The product containing the NH and H 8 is then fed to the process of the present invention.

Suitable catalysts for the preliminary denitrogenation and desulphurization step may comprise one or more hydrogenating metals on compounds thereof chosen from Groups VIa and VIII of the Periodic Table on a acidic refractory oxide support. Suitable metals may be molybdenum together with one or more iron group metals, preferably from 5 to 40% of molybdenum, calculated as the trioxide M and from 1 to 15% of iron group metals, calculated as the divalent oxides (e.g. C00 or NiO). The acidic support may be a known catalytic cracking catalyst, for example catalysts of 50-95% wt. of silica and -50% wt. of alumina, or a support with more than 50% wt. of alumina and less than 50% wt. of an acidic oxide chosen from oxides of elements of Groups II and III and IV of the Periodic Table for example boria, silica, titania or zirconia. Thus suitable catalysts may be chosen from the following ranges of composition.

Percent wt.

Suitable pretreatment conditions, which are preferably chosen to give minimum breakdown to lower boiling products consistent with adequate sulphur and nitrogen removal, may be chosen from:

Temperature, C. 370-460 Pressure, bars gauge 69-207 Space velocity, v./v./hr. 0.4-1.5 Hydrogen gas rate, m. /m. 560-1680 As indicated previously, conversion in the zeolite hydrocracking process must be less than 100% wt. and is preferably from 40-95% wt. more particularly 60-95% wt. conversion to products boiling below 350 C. Thus from 5 to 60% wt. more particularly 5 to 40% wt., is recovered as product boiling above 350 C. The whole of this product boiling above 350 C. may be utilized as lubricating oil basestock, or a portion of it may be withdrawn as lubricating oil basestock and the remainder further hydrocracked by recycle or by passing it to a further zeolite hydrocracking stage. A further zeolite hydrocracking stage if used preferably operates in the absence of NH;,.

The present invention is thus particularly useful for use in a known hydrocracking system having three steps.

(1) Hydrocatalytic denitrogenation and desulphurization;

(2) Partial zeolite hydrocracking in the presence of the NH and H 8 formed in step (1);

(3) Further zeolite hydrocracking with recycle of unconverted feed to extinction in the absence of NH but with H S present.

The product from step (2) is distilled to separate the product into high and low boiling fractions with a cut point in the range 350-450 C. and at least part of the high boiling product is withdrawn as lubricating oil basestock.

The amounts of NH and H 8 required to give any desired degree of VI improvement can readily be determined by comparative experiments if necessary. In practice, petroleum fractions boiling above 350 C. are likely to contain from 0.0; to 0.30% wt. or nitrogen and 0.2 to

3.0% wt. of sulphur. At normal levels of denitrogenation, there will be from 0.018 to 0.363% wt. of NH in the hydocracking zone by weight of feedstock, since the NH is normally removed from the effluent from the hydrocracking zone by scrubbing and is not recycled with the hydrogen-rich recycle gas. H 8 is not normally removed prior to separation of a hydrogen rich recycle gas and the amount present will tend to reach a equilibrium level. For normal ranges of feedstock sulphur contents and operating conditions this equilibrium level may be from 0.1 to 5.0% mol in the hydrogen-rich gas fed by the hydrocracking.

The common zeolites of the faujasite type are the zeolites known as zeolites X and Y. The latter are preferred, these zeolites having, in their dehydrated sodium form, the general formula:

'For hydrocracking activity the zeolite has to be deficient in alkali metal and preferably there is an alkali metal cation deficiency of at least 50% of the theoretical alkalimetal content, and more particularly at least 75%.

A practical upper limit is 95% wt.

As previously stated, the present invention is particularly suitable for use with a faujasite catalyst containing a significant amount of an alkaline earth metal. For the purposes of the present invention the term alkaline earth metal includes magnesium, which is the preferred metal, the other metals being calcium strontium and barium. Preferably the faujasite has from 20-80% wt. of its theoretical alkali metal content replaced by alkaline earth metal cations, this corresponding, in the case of the preferred magnesium faujasite to a magnesium content of 0.9 to 3.8% wt. At least a part of the remaining cations are preferably hydrogen ions, the alkali metal content, being, preferably, 5-20%, i.e. from 0.5-2.0% wt. in the case of sodium.

The hydrogenating metal on the zeolite is desirably a metal from Group VI or VIII of the Periodic Table, particularly the latter. Preferably it is platinum group metal, particularly platinum itself or palladium. The metal is preferably added by ion-exchange and may be present in an amount of 0.01 to 5% wt., more particularly 0.1 to 2% wt. If present in ion exchanged from the amount of the metal should not be such as to take up all the alkali metal cation deficiency.

The presence of NH and H S has the effect in reducing catalyst activity, though they are not permanent poisons. Consequently process conditions have to be more severe to obtain a given level of conversion when operating in the presence of NH and H S and it is this fact which is believed to provide the key to the present invention. For example, a palladium-magnesium-zeolite Y catalyst gave about 50% conversion to products boiling below 371 C. at 360 C. when used in the absence of NH;, and H 8 and only increased the viscosity index of the lubricating oil fraction from 87 to 90. When the same catalyst was used in the presence of NH;, and H 8 the temperature had to be increased to 390 C. to obtain a similar conversion and the viscosity index of the product increased to over 100.

The lubricating oil product can be worked up into finished lubricating oil in known manner, e.g. it can be dewaxed and finished with bauxite or clay or by a hydrofinishing treatment. Dewaxing of the feedstock prior to the hydrocracking can be practiced but it is not preferred. Starting with wax distillate fractions boiling in the range 350 600 C. and having viscosity indices (after dewax ing) of 50-80, finished lubricating oil products with viscosity indices of -125 (as determined by the extended method) can be produced.

The gasoline produced is rich in iso-parafiins and naphthenes and may have a research octane number clear of the order of 85. The amount of middle distillate boiling in the range 200 to 350 C. may be from to 30% Wt. of total product, the ratio of 15-200 C. gasoline EXAMPLE The feedstocks were an Iranian wax distillate and an Iranian distillate with 15% wt. of heavy catalytic cracker 6 Hydrogen gas rate, m. /m.

Wax distillate 1684 Wax distillate+cycle oil 1833 NH, content, percent wt. on feed:

Wax distillate 0.165 Wax distillate+cycle oil 0.155

H S content, percent moi of H gas:

cycle oil. Inspection data on these feedstocks were: Wax distillate 1.7 Wax distillate+cycle oil 1.7 d1 wt Wzltx distilllatti $1 ae puscyceoi I I I o The hydrocracklng gave approximately 60% wt. coni g g fffl fffi ji j 320 293 VISlOli to lower boiling products, the yields of product 5% vol. distilled at are 352 boiling above 371 C. being 37% wt. in the case of the 33% zgtgggfi g :2: g8 g9 wax distillate+cycle oil feed and 35.9% Wt. with the map 546 575 wax distillate feed. In the latter case this was equivalent ggfgf f gggi f gg ffig 2:; fig f??? to 58.6% wt. conversion to material boiling below 288 I l' itrogfinco1tent,p.m.w3 1, 370 1, 285 C. Inspection data on the product boiling above 371 C. gtaas ssgy 5 gag? gt .2; y i In tablehstep i nemaic scosiya 1 cs 7. 2 6. 1011 emtro enation s e an Pour point, C 38 38 p g p step e ydrocrac g Wax distillate plus cycle oil Wax distillate Dewaxed product Dewaxed product boiling above 371 C. boiling above 371 0.

Feed Step 1 Step 2 Feed Step 1 Step 2 Kinematic viscosity at 100 F., est 39. 69 33. 40 64 47. 27 38. 17 Kinematic viscosity at 210 F., est- 6. 29 5. 65 5. 52 7. 32 6. 32 5. 95 Viscosity index 58 102 113 58 87 109 Pour point, 0

3e -15 -9 as -12 -15 1 On dewaxed feed.

Each feedstock was desulphurized and denitrogenated over a nickel-molybdenum-siiica-alumina catalyst with the following inspection data.

Molybdenum, percent wt. 11.3

Nickel, percent wt. 1.8 Silicon, percent wt 2.3 Aluminum, percent wt. 39.3 Pore volume, ml./ g 0.5 Surface area, mP/g 190 The conditions used were:

Temperature, C. 404 Pressure, bars gauge 138 Space velocity, v./v./hr. 0.67 Recycle gas rate mi /m. 1324 A portion of each product was distilled to remove gas and low boiling hydrocarbons and was analyzed to determine the extent of conversion as follows:

Wax Wax distillate distillate plus cycle oil TBP distillation:

IBP-232? 0., percent wt. 232-371 0., percent wt.. 371 0., percent wt Sulphur content, p.p.m. wt Nitrogen content, p.p.m. wt

The total products from the desulphurization/denitrogenation stage including the NH and H 8 produced were each passed over a catalyst of palladium-magnesiumzeolite Y having the following composition.

Space velocity, v./v./hr. 1.4

The viscosity indexes were determined by the extended method (ASTM Test D2270).

The dewaxed products were obtained by dewaxing with methylisobutyl-ketone at 18 C.

The table shows that the desulphurization/denitrogenation step 1 gave, as would have been expected, an increase in VI. It also shows that the zeolite hydrocracking step 2 gave a further improvement in VI and that this further VI improvement was obtained with only a moderate further decrease in viscosity. The table also shows that the feedstock containing the cycle oil gave the higher VI products.

In addition to the lubricating oil basestock, the hydrocracking gave the following additional products:

Wax distillate plus cycle Wax distillate, oil, wt. wt. percent percent 150-204 Gas oil (204370 C.)

We claim:

1. A process for the production of lubricating oil and gasoline by hydrocracking comprising contacting a petroleum feedstock containing a major proportion of material boiling above 350 C. and containing from 0.02 to 0.30% Wt. of nitrogen and 0.2 to 3.0% wt. of sulphur at a temperature of 350 to 450 C., a pressure of 70 to 265 bars gauge, a space velocity of 0.5 to 5 v./v./hr., a hydrogen gas rate of 562 to 2240 m. /m. and in the presence of ammonia and hydrogen sulphide with a catalyst comprising from 0.01 to 5% wt. of a platinum group metal and a faujasite having from 20 to of its theoretical alkali metal replaced by alkaline earth metal to convert from 40 to wt. of the feedstock to material boiling below 350 C. and recovering a product boiling 7 above 350 C. having an improved viscosity index and also a gasoline product boiling below 204 C.

2. A process as claimed in claim 1 wherein the feedstock is a vacuum distillate boiling within the range 350 to 600 C.

3. A process as claimed in claim 1 wherein the pressure is from 100 to 138 bars gauge, the space velocity from 0.5 to 2.0 v./v./hr. and the hydrogen gas rate from 560 to 2240 m. /m.

4. A process as claimed in claim 1 wherein the conversion to products boiling below 350 C. is from 60 to 90% wt.

5. A process as claimed in claim 1 wherein the feedstock is given a preliminary hydrocatalytic denitrogenation and desulphurization and the product, including the NH and H 5 produced, is passed to the hydrocracking.

6. A process as claimed in claim 5 wherein there is from 0.018 to 0.363% wt. of NH; by weight of feedstock in the hydrocracking zone.

7. A process as claimed in claim 5 wherein there is from 0.1 to 5.0% mol of H 8 in the hydrogen rich gas fed to the hydrocracking.

8. A process as claimed in claim 1 wherein the alkaline earth metal is magnesium.

9. A process as claimed in claim 1 wherein the faujasite contains from 5-20% of the theoretical alkali metal content any remaining cations being hydrogen.

References Cited UNITED STATES PATENTS 3,132,087 5/1964 Kelley et al. 20860 3,494,854 2/1970 Gallagher et al. 208-59 3,592,758 7/1971 Inwood 20889 3,654,130 4/1972 Voorhies et al. 20857 3,654,133 4/1972 Olson 20859 3,658,689 4/ 1972 Steinmetz 208-46 3,666,657 5/1972 Thompson et a1 20858 3,732,156 8/1973 Bennett et a1. 208111 FOREIGN PATENTS 2,105,832 7/ 1971 German Olfen. 20858 DELBERT E. GANTZ, Primary Examiner G. E. SCHMITKONS, Assistant Examiner US. Cl. X.R.

208Dig. 2, 18, 58, 89; 252-455 Z, 473

. A I fiNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 i 804 74 2 v I Dated i lti l l lgz Robert. Nci'l Bennett ct a1 Inventor-(H) ,w-

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:-

Column 4, line 11, "by" should read to. line 18,

OaA1 O .37 SiO should read Na O-zAl O z3-7SiO line 44 "from" should read form Column 6 line 4, "NH" should read NH: lines 11 and 12, "convrsion" should read conversion --4.

Signed and sealed this 24th day of September 1974.

(SEAL) Attest: v

MCCOY M. GIBSON, JR. I c. MARSHALL DANN Arresting Officer A Commissioner of Patents USCOMM-DC 603764 69 FORM PO-105O (10-69) nr u.s. sovzmmzur vmmms omc: was o-sss-su, 

